What this is about
After the BLUTZUCKER complex, STOFFWECHSEL (metabolism) is the second NATURTREU product aimed directly at my subject area. The full product name is “Metabolism complex for metabolism and blood glucose level*” – with two asterisks referring in the small print to chromium and choline. It is precisely this construction that I am examining.
At a glance
| Manufacturer | NATURTREU (ZENKOH GmbH, Leverkusen) |
| Form | 120 capsules, one month’s supply |
| Price | approx. €24.99 (as of July 2026) |
| Key ingredients | L-carnitine, bitter melon, green tea extract, choline, chromium |
| Positioning | Fat and carbohydrate metabolism, blood glucose level |
| Production | Germany, independent laboratory testing |
The ingredients in detail
Chromium
As with the BLUTZUCKER complex, chromium carries the authorised claim “contributes to the maintenance of normal blood glucose levels”. This is a statement about normal function, not about lowering elevated values. the research on chromium in disturbed glucose metabolism remains heterogeneous with at best small effects .
Choline
Choline carries the authorised claim “contributes to normal lipid metabolism” and to normal liver function. This is real and documented – but it concerns fat metabolism and the liver, not blood sugar. The indirect route is interesting: fatty liver is closely linked to insulin resistance, and its regression is a central mechanism of remission. Whether choline supplementation contributes anything here in normally supplied people is, however, not shown .
L-carnitine
L-carnitine transports long-chain fatty acids into the mitochondria – a real, well-understood mechanism. The conclusion “more carnitine = more fat burning” is nevertheless not documented: in healthy people on a mixed diet, the carnitine store is full, and oral intake barely raises muscle content. Studies on weight loss show at most very small effects . For blood sugar there are individual studies with an inconsistent picture .
Bitter melon (Momordica charantia)
This is the pharmacologically most interesting component. Bitter melon contains compounds with insulin-like activity, and the plant is used in several traditional medical systems for diabetes. Clinical studies in humans show mixed results: some find moderate reductions in fasting glucose, others no effect; Cochrane reviews concluded that the research is insufficient for a recommendation .
Important safety note: precisely because bitter melon can genuinely lower blood sugar, combining it with blood-sugar-lowering medication is a real interaction point. The rule here: clarify medically, do not experiment on your own.
Green tea extract
Green tea catechins (especially EGCG) are associated with favourable effects on insulin sensitivity and body weight; effect sizes in meta-analyses are small . Note: EFSA has pointed to a risk of liver damage at high EGCG doses from extracts (from around 800 mg EGCG/day). Anyone combining several green-tea-containing preparations should keep an eye on the total dose.
What strikes me about this product
The formulation is broader than the BLUTZUCKER complex and targets fat rather than glucose metabolism. This is consistent with the claims: chromium and choline carry the legally permissible statements, while L-carnitine, bitter melon and green tea convey the substantive expectation without being allowed to carry effect statements themselves.
The honest summary: one ingredient with genuine pharmacological potential (bitter melon), two with authorised but narrowly framed claims (chromium, choline), and two with a weak to moderate study basis (L-carnitine, green tea). For a product in this category that is not a bad balance – just far removed from what the name suggests.
My classification for my own path
For me, what decides my blood sugar remains what and how much I eat, how I move and how my weight develops . A metabolism complex cannot replace these levers. What it can do at best: make a small contribution when the basics are right.
What I explicitly do not do: take bitter melon alongside blood-sugar-lowering medication without discussing it medically.
My test plan (pending)
- CGM course over 4 weeks with standardised test meals before and during intake.
- Fasting values in daily comparison – the parameter where bitter melon could most likely show something.
- Tolerability: bitter melon can cause gastrointestinal complaints; I document this too.
- Honest limits: unblinded n=1 trial, no causal statement possible.
Sources
- Product information NATURTREU STOFFWECHSEL: composition with L-carnitine, bitter melon, green tea, choline and chromium (naturtreu.de, as of July 2026).
- EU Register of authorised health claims: chromium (normal blood glucose level), choline (normal lipid metabolism, liver function).
- Cochrane review on Momordica charantia (bitter melon) in diabetes mellitus: insufficient research for a recommendation.
- EFSA assessment of green tea catechins (EGCG) and liver safety at high doses from extracts.
- Reviews on L-carnitine supplementation, muscle carnitine and weight management: small effect sizes.
- Lean MEJ et al.: DiRECT trial on remission in type 2 diabetes through weight management, The Lancet.